/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package demo.spark.examples.streaming;

import org.apache.spark.SparkConf;
import org.apache.spark.api.java.function.Function;
import org.apache.spark.streaming.*;
import org.apache.spark.streaming.api.java.*;
import org.apache.spark.streaming.flume.FlumeUtils;
import org.apache.spark.streaming.flume.SparkFlumeEvent;

/**
 * Produces a count of events received from Flume.
 * <p>
 * This should be used in conjunction with an AvroSink in Flume. It will start
 * an Avro server on at the request host:port address and listen for requests.
 * Your Flume AvroSink should be pointed to this address.
 * <p>
 * Usage: JavaFlumeEventCount <host> <port>
 * <host> is the host the Flume receiver will be started on - a receiver
 * creates a server and listens for flume events.
 * <port> is the port the Flume receiver will listen on.
 * <p>
 * To run this example:
 * `$ bin/run-example demo.spark.examples.streaming.JavaFlumeEventCount <host> <port>`
 */
public final class JavaFlumeEventCount {
    private JavaFlumeEventCount() {
    }

    public static void main(String[] args) throws InterruptedException {
        if (args.length != 2) {
            System.err.println("Usage: JavaFlumeEventCount <host> <port>");
            System.exit(1);
        }


        String host = args[0];
        int port = Integer.parseInt(args[1]);

        Duration batchInterval = new Duration(2000);
        SparkConf sparkConf = new SparkConf()
                .setAppName("JavaFlumeEventCount");
        JavaStreamingContext ssc = new JavaStreamingContext(sparkConf, batchInterval);
        JavaReceiverInputDStream<SparkFlumeEvent> flumeStream = FlumeUtils.createStream(ssc, host, port);

        JavaDStream<Long> longJavaDStream = flumeStream.count();

        longJavaDStream.map(
                new Function<Long, String>() {
                    @Override
                    public String call(Long in) {
                        return "Received " + in + " flume events.";
                    }
                }).print();

        ssc.start();
        ssc.awaitTermination();
    }
}
